The ability to pass a numeric argument to gensym has been deprecated;
explicitly binding*gensym-counter* is now stylistically preferred.
(The somewhat baroque conventions for the optional argument are historical
in nature, and supported primarily for compatibility with older dialects
of Lisp. In modern code, it is recommended that the only kind of argument
used be a string prefix. In general, though, to obtain more flexible control
of the new-symbol's name, consider using make-symbol instead.)